Nowadays the convenience of mobile appliances like IC cards, smart phones and notebook computers brings us better life but also into privacy threat. The more widespread these mobile appliances are, the more significant the issue on personal security is. As a result, the demand for user authentication is becoming more and more important. Some biometrics, such as fingerprint, hand geometry, iris and voice print, have been popularly applied in authentication. Because of the property of low-cost, easy integration and high reliability, many researches have been reported on fingerprint acquisition. Fingerprint acquisition can be performed by capacitive sensing scheme. However, parasitic capacitance nearby a fingerprint sensor usually reduces the sensitivity and the output dynamic range. It may therefore be desirable to have a fingerprint sensor that is able to alleviate the effect of parasitic capacitance.